The blood and custard didn't look as good as the original chocolate and cream. A splendid image of one of the thirty eight Railcars which eventually made up the fleet within the former G.W.R. , this example being W15W with its rouded and smoothed leading and trailing ends , contrasting with the sharp and wedge shaped design of other examples . Built by Swiondon in conjunction with A.E.C. of Southall , the original versions soon had their single power plant replaced by twin engines thereby increasing their power ouitput from 121 h.p. to 242 h.p. and W15W had a capacity of no less than seventy seats . Known as ' Flying Bananas ' the Railcars enjoyed a wide and varied range of duties , and there were many variations in the design of individual units , two of which , numbers W17W and W34W , were designed and used just for express parcels duties , without any provision for passenger seating whatsoever.